Conventionally, various types of room-temperature-curable organopolysiloxane compositions have been known which, upon coming into contact with moisture in the air, crosslinks to each other by condensation reaction and cures to give an elastomer (silicone rubber) at room temperature. Among these compositions, dealcoholization-type organopolysiloxane compositions, which generate alcohol upon crosslinking to each other by condensation reaction and curing, do not generate unpleasant odor or cause metal corrosion and therefore have been suitably used in sealing, adhesive, and coating applications in electrical and electronic devices and the like.
Typical examples of the dealcoholization-type organopolysiloxane compositions include a composition composed of a polyorganosiloxane end-capped with a hydroxyl group, an alkoxysilane, and an organic titanium compound; a composition composed of a polyorganosiloxane end-capped with an alkoxysilyl group, an alkoxysilane, and an alkoxy titanium; a composition composed of a linear polyorganosiloxane the terminal of which has been blocked by an alkoxysilyl group containing a silethylene group, an alkoxysilane, and an alkoxy titanium; and a composition composed of a polyorganosiloxane end-capped with a hydroxyl group or a polyorganosiloxane end-capped with an alkoxy group and an alkoxy-α-silyl ester compound (Patent Literatures 1 to 4).
These compositions have storage stability, water resistance, and humidity resistance to some extent, but do not fully satisfy the requirements for these properties. Nor do these compositions fully satisfy the requirements for rapid curability.
As described above, organosiloxane polymers having a reactive (hydrolyzable) alkoxysilyl group at its end have been conventionally known. Because being end-capped with an alkoxysilyl group, these polymers are unlikely to have their curability subjected to changes (degradation) with time and therefore have excellent storage stability. In addition, these polymers have their workability (viscosity, thixotropy) optionally controllable, crosslink to each other upon reaction with moisture in the air and give an elastomer, and have excellent properties (hardness, tensile strength, elongation at break).
However, the dealcoholization-type organopolysiloxane compositions, compared to conventionally known other types of organosiloxane compositions such as deoximation type, deacetic acid type, and deacetonation type organosiloxane compositions, are low in reactivity with moisture in the air and therefore are insufficient in curability.
In the circumstances, there have been developed room-temperature-curable organopolysiloxane compositions that are excellent in rapid curability and can give a cured product that is excellent in humidity resistance (curability after storage under anti-humidity conditions). However, none of such compositions can be advantageously produced on an industrial scale.